This invention relates to a shoe for use in removing the detritus and sedimentary matter that accumulates in the invert of sewers.
At present, this material is removed in a variety of ways depending upon the size of the sewer. With large diameter sewers this matter is removed by gangs of men called flushers who use shovels and skips within the sewers pushing the loaded skips to manholes where they are removed and unloaded. Not only is this job undesirable but also this technique does not provide a very effective removal of the detritus and sedimentary matter. With smaller diameter sewers some attempts have been made to winch with a wire and cone attachment through from one end to the other but nowadays jetting techniques are widely used in which a hose containing water under high pressure is passed through the sewer with water being jetted from a nozzle at the end of the hose to scour the detritus and sedimentary matter from the sewer as the hose moves along. In practice, a portion of the water is jetted in the backwards direction to drive the hose through the sewer. This technique is generally successful but the apparatus is very expensive and, overall, has a low productivity because of the large proportion of down time that occurs while it is being set up, dismantled and recharged.